Multilayer capacitor

ABSTRACT

A multilayer capacitor whose equivalent series inductance is reduced includes a capacitor main body having a generally rectangular parallelpiped shape with two principal surfaces in a face-to-face relationship with each other and four side surfaces connecting the principal surfaces. A capacitor unit is formed in the capacitor main body by a respective pair of first and second internal electrodes disposed in the main body in a face-to-face relationship with a dielectric material layer interposed therebetween. At least three first external electrodes are located on respective ones of the side surfaces of the capacitor main body, with at least one of the first external electrodes being located on each of at least three of the side surfaces. The first internal electrode has at least three first lead electrodes, each of which extends to and is electrically coupled to a respective one of the first external electrodes. A plurality of second external electrodes are located on respective side surfaces of the capacitor main body and the second internal electrode has an equal plurality of second lead electrodes, each extending to and being electrically coupled to a respective one of the second external electrodes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multilayer capacitor and, moreparticularly, to a multilayer capacitor which can be advantageously usedin high frequency circuits.

2. Description of the Related Art

Conventional multilayer capacitors include that described in JapaneseUnexamined Patent Publication No. H2-256216 in which a multilayercapacitor 1, as shown in FIGS. 15 through 17, is disclosed. FIG. 15 is aplan view of the external appearance of the multilayer capacitor 1. FIG.16 is a plan view of a first section of the multilayer capacitor 1showing a first electrode 10 located on one surface of one internaldielectric layer 9 of the capacitor 1. FIG. 17 is a plan view of asecond section of the multilayer capacitor 1 showing a second electrode11 located on one surface of a differential internal dielectric layer 9of the capacitor 1.

Referring to FIGS. 15-17, the multilayer capacitor 1 includes acapacitor main body 8 in the form of a rectangular parallelpiped havingtwo principal surfaces 2 and 3 in a face-to-face relationship with eachother and four side surfaces 4, 5, 6 and 7 connecting the principalsurfaces 2 and 3. The capacitor main body 8 includes a plurality ofdielectric layers 9 (FIGS. 16-17) made of, for example, a ceramicdielectric material. Each of the dielectrical layers is generally planarin shape and lies generally parallel to the principal surfaces 2 and 3.At least a pair of first and second internal electrodes 10 and 11 areprovided on respective surfaces of the dielectric layers 9 in aface-to-face relationship with each other with a dielectric layer 9interposed therebetween to form a capacitor unit.

The first internal electrode 10 is formed with four lead electrodes 12,13, 14 and 15 which extend to two opposing side surfaces 4 and 6, asshown.

Each lead electrode 12, 13, 14 and 15 is coupled to a respectiveexternal terminal electrode 16, 17, 18 and 19 provided on the sidesurfaces 4 and 6 of the capacitor main body 8. Specifically, the leadelectrodes 12 and 13 are connected to the external terminal electrodes16 and 17, respectively, which are located on the side surface 4, andthe lead electrodes 14 and 15 are connected to the external terminalelectrodes 18 and 19, respectively, which are located on the sidesurface 6.

Referring to FIG. 17, the second internal electrode 11 is also formedwith four lead electrodes 20, 21, 22 and 23 which extend to the sidesurfaces 4 and 6, respectively. More specifically, the lead electrodes20 and 21 extend to positions on the side surface 4 which are differentfrom the positions to which the lead electrodes 12 and 13 extend, andthe lead electrodes 22 and 23 extend to positions on the side surface 6of the main body 8 which are different from the positions to which thelead electrodes 14 and 15 extend.

The lead electrodes 20 through 23 are electrically coupled to externalterminal electrodes 24, 25, 26 and 27, respectively. External terminalelectrodes 24 and 25 are located on the side surface 4 at positionswhich are different from those of the external terminal electrodes 16and 17. External terminal electrodes 26 and 27 are located on the sidesurface 6 at positions which are different from the positions of theexternal terminal electrodes 18 and 19.

Thus, the plurality of first external terminal electrodes 16 through 19and the plurality of second external terminal electrodes 24 through 27are arranged on the two side surfaces 4 and 6 such that they alternateadjacently to each other.

FIG. 18 illustrates current flowing through the multilayer capacitor 1as viewed in plan view corresponding to FIG. 17. In FIG. 18, firstinternal electrode 10 and second internal electrode 11, shown withbroken and solid lines, respectively, are shown in an overlappingrelationship.

In FIG. 18, the arrows indicate typical current paths and directions. Inthe state illustrated, current flows from each of the external terminalelectrodes 24 through 27 to each of the external terminal electrodes 16through 19. Because an alternating current is used, the direction ofcurrent flow will reverse periodically.

When the currents flow, magnetic flux is induced. The direction of theflux is determined by the direction of the currents to produceself-inductance components. Since the currents flow in variousdirections at central regions 28 (indicated by circles) of the internalelectrodes 10 and 11, the induced magnetic flux generated by the variouscurrents is canceled and substantially no net magnetic flux is producedin those regions.

The current in the vicinity of each of the external terminal electrodes16 through 19 and 24 through 27 tends to flow toward each of theexternal terminal electrodes 16 through 19 and away from each of theexternal terminal electrodes 24 through 27. There are currents that flowto the left and right as viewed in FIG. 18 to spread at an angle ofabout 180 degrees. As a result, a major part of magnetic flux iscanceled and there is no significant generation of net magnetic flux inthese areas.

Therefore, in the multilayer capacitor 1 shown in FIGS. 15 through 17,the generation of self-inductance is suppressed in the areas pointsdescribed above to reduce equivalent series induction (hereinafter"ESL").

However, currents flow substantially in the same direction in thevicinity of each of the side surfaces 5 and 7 on which no externalterminal electrodes are provided, i.e., at each of the left and rightedge portions indicated by hatching in FIG. 18. This results insubstantially no cancellation of magnetic flux in these areas andsignificant net self-inductance is created. Therefore, the measurestaken to reduce ESL in the multilayer capacitor 1 shown in FIGS. 15through 17 is less than desirable.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a multilayercapacitor which more effectively reduces ESL.

In accordance with one aspect of the present invention, a multilayercapacitor, comprises:

a capacitor main body having a generally rectangular parallelpiped shapewith two principal surfaces in a face-to-face relationship with eachother and four side surfaces connecting said principal surfaces;

m capacitor units formed in said capacitor main body, m being an integergreater than or equal to one, each of said capacitor units being formedby a respective pair of first and second internal electrodes disposed insaid main body in a face-to-face relationship with a dielectric materiallayer interposed therebetween to form a capacitor unit;

n first external electrodes, n being an integer greater than 2, each ofsaid first external electrodes being located on a respective one of saidside surfaces of said capacitor main body, at least one of said firstexternal electrodes being located on each of at least three of said sidesurfaces;

said first internal electrode having n first lead electrodes, each ofsaid first lead electrodes extending to and being electrically coupledto a respective one of said first external electrodes;

p second external electrodes, p being an integer greater than 1, each ofsaid second external electrodes being located on a respective one ofsaid side surfaces of said capacitor main body; and

said second internal electrode having p second lead electrodes, each ofsaid second lead electrodes extending to and being electrically coupledto a respective one of said second external electrodes.

The internal and lead electrodes are preferably arranged in such amanner that when currents of different polarity are applied to saidfirst and second internal electrodes, the net induced inductance in thearea of all four of said side surfaces is substantially zero.

In one embodiment of the present invention, the first internal electrodeis formed with at least four first lead electrodes which extendrespectively to respective ones of the four side surfaces. An equalnumber of first external terminal electrodes are provided. At least oneof the first external terminal electrodes is located on each of the fourside surfaces.

In this embodiment, the second internal electrode is formed with atleast four second lead electrodes which extend to respective ones of thefour side surfaces. An equal number of second external terminalelectrodes are provided. At least one of the second external terminalelectrodes is located on each of the four side surfaces.

It is more advantageous if the above-described configuration is employedfor both of the first and second internal electrodes.

In another embodiment, for each side surface which has both a first anda second external terminal electrode, each of the first externalterminal electrodes located on that surface is located adjacent to one acorresponding second external terminal electrode located on that sidesurface. It is more advantageous if all of the first external terminalelectrodes and all of the second external terminal electrodes arearranged such that they alternate with each other throughout the fourside surfaces.

In yet another embodiment, all of the external terminal electrodes arearranged such that they are not adjacent to any other external electrodewhich is connected to the same internal electrode.

In still another embodiment, the first external internal electrode isformed with three first lead electrodes which extend respectively tothree of the side surfaces. The second internal electrode is formed withtwo second lead electrodes which extend respectively to two of the sidesurfaces, one of which does have a first external electrode.

In the most preferred embodiment, at least one of the first and at leastone of the second external terminal electrodes is provided on each ofthe four side surfaces.

A plurality of capacitor units can be provided in the multilayercapacitor. Each capacitor unit includes a respective pair of first andsecond internal electrodes with a respective dielectric layer locatedtherebetween.

According to the present invention, the effect of reducing ESL can beexpected from effective cancellation of magnetic and reduction of thelengths of currents achieved by providing a third internal electrodefacing at least either the first or second internal electrodes with adielectric material layer interposed therebetween. The third internalelectrode is formed with at least two third lead electrodes which extendto respective ones of the side surfaces. An equal number of thirdexternal terminal electrodes are provided on the corresponding sidesurfaces and are electrically coupled to respective ones of the thirdlead electrode.

In the above-described embodiment, when all of the first, second andthird external terminal electrodes are arranged in the same order ofarrangement repeated throughout the four side surfaces, the variouscomponents of magnetic flux can be more effectively canceled and thelengths of the current paths can be shortened further for a furtherreduction of ESL.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawing several forms which are presently preferred, it beingunderstood, however, that the invention is not limited to the precisearrangements and instrumentalities shown.

FIG. 1 is a plan view of a multilayer capacitor 31 according to a firstembodiment of the present invention;

FIG. 2 is a plan view of the multilayer capacitor 31 shown in FIG. 1showing an internal structure thereof in the form of a section alongwhich a first internal electrode 40 extends;

FIG. 3 is a plan view of the multilayer capacitor shown 31 in FIG. 1showing an internal structure thereof in the form of a section alongwhich a second internal electrode 41 extends;

FIG. 4 is a plan view illustrating currents flowing in the multilayercapacitor 31;

FIG. 5 is a plan view of a multilayer capacitor 71 according to a secondembodiment of the invention showing the external appearance thereof;

FIG. 6 is a plan view of the multilayer capacitor 71 shown in FIG. 5showing an internal structure thereof in the form of a section alongwhich a first internal electrode 40a extends;

FIG. 7 is a plan view of the multilayer capacitor 71 shown in FIG. 5showing an internal structure thereof in the form of a section alongwhich a second internal electrode 41a extends;

FIG. 8 is a plan view of a multilayer capacitor 81 according to a thirdembodiment of the invention showing the external appearance thereof;

FIG. 9 is a plan view of the multilayer capacitor 81 shown in FIG. 8showing an internal structure thereof in the form of a section alongwhich a third internal electrode 82 extends;

FIG. 10 is a plan view of the multilayer capacitor 81 shown in FIG. 8showing an internal structure thereof in the form of a section alongwhich a first internal electrode 40b extends;

FIG. 11 is a plan view of the multilayer capacitor 81 shown in FIG. 8showing an internal structure thereof in the form of a section alongwhich a second internal electrode 41b extends;

FIG. 12 is a plan view of a multilayer capacitor 91 according to afourth embodiment of the invention showing the external appearancethereof;

FIG. 13 is a plan view of the multilayer capacitor 91 shown in FIG. 12showing an internal structure thereof in the form of a section alongwhich a first internal electrode 40c extends;

FIG. 14 is a plan view of the multilayer capacitor 91 shown in FIG. 12showing an internal structure thereof in the form of a section alongwhich a second internal electrode 41c extends;

FIG. 15 is a plan view of a conventional multilayer capacitor 1 which isof interest to the present invention showing the external appearancethereof;

FIG. 16 is a plan view of the multilayer capacitor 1 shown in FIG. 15showing an internal structure thereof in the form of a section alongwhich a first internal electrode 10 extends;

FIG. 17 is a plan view of the multilayer capacitor 1 shown in FIG. 15showing an internal structure thereof in the form of a section alongwhich a second internal electrode 11 extends;

FIG. 18 is a plan view illustrating currents flowing in the multilayercapacitor 1 shown in FIG. 15;

FIG. 19 is a plan view of a multilayer capacitor 101 according to afifth embodiment of the present invention;

FIG. 20 is a plan view of the multilayer capacitor 101 shown in FIG. 19showing an internal structure thereof in the form of a section alongwhich a first internal electrode 40d extends; and

FIG. 21 is a plan view of the multilayer capacitor 101 shown in FIG. 10showing an internal structure thereof in the form of a section alongwhich a second internal electrode 41d extends.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

Referring now to the drawings, wherein like numerals indicate likeelements, there is shown in FIGS. 1 through 3 a first embodiment of amultilayer capacitor constructed in accordance with the principles ofthe present invention and designated generally as 31. FIGS. 1 through 3correspond to FIGS. 15 through 17.

FIG. 1 is a plan view of the external appearance multilayer capacitor31. FIG. 2 is a plan view multilayer capacitor 31 showing a firstinternal electrode 40 located on one surface of a first internaldielectric layer 39 of the capacitor 31. FIG. 3 is a plan view of asecond section of the multilayer capacitor 31 showing a second internalelectrode 41 located on one surface of a second internal dielectriclayer 39 of the capacitor 31.

Multilayer capacitor 31 includes a capacitor main body 38 in the form ofa rectangular parallelpiped having two opposed principal surfaces 32 and33 and four side surfaces 34, 35, 36 and 37 extending therebetween. Thecapacitor main body 38 includes a plurality of generally planardielectric layers 39 made of, for example, a ceramic dielectricmaterial. The main surfaces of the dielectric layers 39 are situatedgenerally parallel to the principal surfaces 32, 33 of the capacitormain body 38. At least a pair of first and second internal electrodes 40and 41 are provided in a face-to-face relationship with each other witha dielectric material layer 39 interposed therebetween, each such pairof internal electrodes forming a respective capacitor unit.

As shown in FIG. 2, the first internal electrode 40 has six leadelectrodes 42, 43, 44, 45, 46 and 47, each of which extends to arespective one of the four side surfaces 34 through 37. Particularly,the lead electrodes 42 and 43 extend to the side surface 34; the leadelectrode 44 extends to the side surface 35; the lead electrodes 45 and46 extend to the side surface 36; and the lead electrode 47 extends tothe side surface 37.

Each lead electrode 42-47 is electrically coupled to a respectiveexternal terminal electrodes 48-53. The external terminal electrodes 48and 49, connected to the lead electrodes 42 and 43, respectively, arelocated on the side surface 34; the external terminal electrode 50,connected to the lead electrode 44, is located on the side surface 35;the external terminal electrodes 51 and 52, connected to the leadelectrodes 45 and 46, respectively, are located on the side surface 36;and the external terminal electrode 53, connected to the lead electrode47, is located on the side surface 37.

As shown in FIG. 3, the internal electrode 41 is formed with six secondlead electrodes 54, 55, 56, 57, 58 and 59, each of which extend to arespective one of the four side surfaces 34 through 37. Morespecifically, the lead electrodes 54 and 55 extend to side surface 34;lead electrode 56 extends to side surface 35; lead electrodes 57 and 58extend to side surface 36; and lead electrode 59 extends to the sidesurface 37.

The positions on the side surfaces 34 through 37 to which the respectivelead electrodes 54 through 59 extend are different from the positions towhich the respective lead electrodes 42 through 47 extend.

External terminal electrodes 60, 61, 62, 63, 64 and 65, which areelectrically coupled to respective lead electrodes 54 through 59, areprovided on the side surfaces 34 through 37 a positions which aredifferent than the positions of the external terminal electrodes 48through 53. External terminal electrodes 60 and 61, connected to leadelectrodes 54 and 55, respectively, are located on side surface 34;external terminal electrode 62, connected to lead electrode 56, islocated on side surface 35; external terminal electrodes 63 and 64,connected to lead electrodes 57 and 58, respectively, are located onside surface 36; and external terminal electrode 65, connected to leadelectrode 59, are located on side surface 37.

The external terminal electrodes 48 through 53 are arranged in aninterleaved manner such that no two external electrodes which areelectrically coupled to the same internal electrode 40 or 41 areadjacent one another. In operation, the polarization of the first andsecond internal electrodes 40, 41 are preferably opposite to oneanother.

In order to increase the capacity of the multilayer capacitor 31,additional pairs of internal electrodes can be provided to defineadditional capacitor units. For example, the multilayer capacitor 31 caninclude two sets of capacitor units, each set being defined by arespective pair of first and second internal electrodes 40, 41 separatedby a respective dielectric layer. The plurality of capacitor units arepreferably connected in parallel by at least either appropriate ones ofthe first external terminal electrodes 48 through 53 or the secondexternal terminal electrodes 60 through 65.

Each of the external terminal electrodes 48 through 53 and 60 through 65is preferably formed so as to extend not only on the side surfaces 34through 37 but also onto a part of each of the principal surfaces 32 and33.

FIG. 4 illustrates various currents flowing in the multilayer capacitor31. In FIG. 4, the first internal electrode 40 is indicated by a brokenline and the second internal electrode 41 is indicated by a solid line,the two electrodes being illustrated in an overlapping relationship.

As apparent from these typical paths and the directions of current flowindicated by the arrows in FIG. 4 (the direction of current flowindicates that direction of each of the noted current paths at a givenpoint in time, the direction of the flow of current through these pathswill alternate periodically), a current flows from each of the secondexternal terminal electrodes 60 through 65 to each of the first externalterminal electrodes 48 through 53. When such currents flow, inducedmagnetic flux is generated.

As in the prior art, the various components of the induced flux at thecentral regions 66 indicated by the circles cancel one another outbecause currents flow in various directions. Similarly, the variouscomponents of the induced flux in the areas of the side surfaces 34 and36 tend to cancel one another. In this connection, current flow in thearea of side surfaces 34 and 36 is very similar to that of the prior artof FIG. 18.

However, the embodiment of FIGS. 1-4 produces a much more desirableresult in the areas 67 adjacent the side surfaces 35, 37. Since thefirst external terminal electrodes 50 and 53 and the second externalterminal electrodes 62 and 65 are provided at the side surfaces 34 and36, there is no significant net current flow in the areas 67 and nosignificant generation of net magnetic flux.

As a result, the degree of net induced magnetic flux generated over theentire region of the multilayer capacitor 31 is significantly reduced,thereby allowing the ESL to be suppressed to a very low level.

Another advantage of this embodiment is that the current paths betweeneach of the electrodes is reduced. Particularly, each of the first leadelectrodes 42 through 47 (and the first external terminal electrodes 48through 53) is located relatively close to its adjacent second leadelectrode 54 through 59 (and the second external terminal electrode 60through 64) compared to the prior art of FIG. 18. This reduces thelengths of the current paths and thereby reduces self-inductancecomponents produced between them.

Second Embodiment

FIGS. 5 through 7 show a multilayer capacitor 71 according to a secondembodiment of the present invention. FIG. 5 is a plan view of theexternal appearance of the multilayer capacitor 71. FIG. 6 is a planview showing one surface of an internal dielectric layer 39 of themultilayer capacitor 71 having a first internal electrode 40a locatedthereon. FIG. 7 is a plan view showing one surface of a different one ofthe internal dielectric layers 39 of the multilayer capacitor 71 havinga second internal electrode 41a located thereon.

FIGS. 5 through 7 respectively correspond to FIGS. 1 through 3 of thefirst embodiment. In FIGS. 5 through 7, elements corresponding toelements shown in FIGS. 1 through 3 are indicated by like referencenumbers and will not be described here to avoid duplication.

Referring to FIG. 6, the first internal electrode 40a is formed withfive lead electrodes 42, 43, 45, 46 and 47a which extend to respectiveside surfaces 34, 36 and 37. The multilayer capacitor 71 is differentfrom the multilayer capacitor 31 of the first embodiment in that themultilayer capacitor 71 has no lead electrode extending to side surface35. Additionally, lead electrode 47a extends to the middle of the sidesurface 37, whereas lead electrode 47 extends to the upper half of sidesurface 37.

The five lead electrodes 42 through 47a are electrically coupled to fiveexternal terminal electrodes 48, 49, 51, 52 and 53a, respectively. Thefive external electrodes 48, 49, 51, 52 and 53a, are each located on oneof the three side surfaces 34, 36 and 37. The multilayer capacitor 71 isdifferent from the multilayer capacitor 31 of the first embodiment inthat the multilayer capacitor 71 has no external terminal correspondingto the first external terminal electrode 50 and in that the externalterminal electrode 53a is different in location from the externalterminal electrode 53.

Referring to FIG. 7, a second internal electrode 41a has five leadelectrodes 54, 55, 56a, 57 and 58 which extend to respective sidesurfaces 34 through 36. The multilayer capacitor 71 is different fromthe multilayer capacitor 31 of the first embodiment in that it has nolead electrode extending to the side surface 37 and in that the leadelectrode 56a which extends to the side surface 35 extends to the middleof the side surface 35, rather than the bottom of the side surface 35 asis the case with lead electrode 56 of the first embodiment.

Each of the lead electrodes 54 through 58 is electrically coupled to arespective external terminal electrode 60, 61, 62a, 63 and 64. Each ofthese terminal electrodes are provided on a respective side surface 34through 36. The multilayer capacitor 71 is different from the multilayercapacitor 31 of the first embodiment in that it has no external terminalcorresponding to the external terminal electrode 65 and in that theexternal terminal electrode 62a is located in a different position thanthe external terminal electrode 62.

If desired, the capacity of multilayer capacitor 71 can be increased byproviding a plurality of capacitive units, each defined by a respectiveset of internal electrodes 40a, 41a, separated by a respectivedielectric layer 38. The plurality of capacitor units are then connectedin parallel by appropriate ones of the external terminal electrodes 48through 53a or 60 through 64.

In the second embodiment of the invention, each of the external terminalelectrodes 48, 49, 51 and 52 coupled to the first internal electrode 40ais located adjacent at least one of the external terminal electrodes 60,61, 63 and 64 coupled to internal electrode 41a. Further, only thesecond external terminal electrode 62a is located on the side surface35, and only the first external terminal electrode 53a is located on theside surface 37. By providing the external terminal electrodes 62a and53a on the side surfaces 35 and 37, respectively, it is possible todirect the flow of the currents on the internal electrodes 40a and 41ain various directions to achieve a level of cancellation of magneticflux that is higher than that which is achievable in the conventionalmultilayer capacitor 1 shown in FIGS. 15 through 17. It is also possibleto reduce the length of the path of these currents thereby furtherreducing the induced inductance components.

Third Embodiment

FIGS. 8 through 11 show a multilayer capacitor 81 according to a thirdembodiment of the present invention. FIG. 8 is a plan view of theexternal appearance of the multilayer capacitor 81. FIG. 9 is a planview of the surface of one of the internal dielectric layers 39 of themultilayer capacitor 81 having a first internal electrode 82 formedthereon. FIG. 10 is a plan view of the surface of one of the internaldielectric layers 39 of the multilayer capacitor 81 having a secondinternal electrode 40b formed thereon. FIG. 11 is a plan view of thesurface of one of the internal dielectric layers 39 of the multilayercapacitor 81 having a third internal electrode 41b formed thereon.

In FIGS. 8 through 11, elements corresponding to elements shown in FIGS.1 through 3 are indicated by like reference numbers and will not bedescribed here to avoid duplication.

The multilayer capacitor 81 of the third embodiment of the inventionincludes a third internal electrode 82 facing at least either the firstinternal electrode 40b or second internal electrode 41b with adielectric material layer 39 interposed therebetween. The third internalelectrode 82 is formed with four lead electrodes 83, 84, 85 and 86, eachof which extends to a respective side surface 34 and 36. Morespecifically, lead electrodes 83 and 84 extend to side surface 34, andlead electrodes 85 and 86 extend to side surface 36.

External terminal electrodes 87, 88, 89 and 90, which are electricallycoupled to the lead electrodes 83 through 86, respectively, are providedon respective side surfaces 34 and 36. The multilayer capacitor 81 isdifferent from the multilayer capacitor 31 of the first embodiment inthat it includes the third external terminal electrodes 87 and 90provided, respectively, in the positions where the first externalterminal electrodes 48 and 52 are provided on the multilayer capacitor31 of the first embodiment and includes the third external terminalelectrodes 88 and 89 provided respectively in the positions where thesecond external terminal electrodes 61 and 63 are provided on themultilayer capacitor 31.

Referring to FIG. 10, a first internal electrode 40b has four first leadelectrodes 42b, 44, 45b and 47 which extend to respective side surfaces34 through 37. The first internal electrode 40b of the multilayercapacitor 81 is different from the multilayer capacitor 31 of the firstembodiment in that it has only one lead electrode 42b which extends toside surface 34 and one lead electrode 45b which extends to side surface36.

Four first external terminal electrodes 48b, 50, 51b and 53 areelectrically coupled to the four first lead electrodes 42b through 47,respectively, and are provided on the four side surfaces 34 through 37,respectively. The multilayer capacitor 81 is different from themultilayer capacitor 31 of the first embodiment in that it includes thefirst external terminal electrodes 48b and 51b provided respectively inthe positions where the second external terminal electrodes 60 and 64are provided on the multilayer capacitor 31.

Referring to FIG. 11, a second internal electrode 41b has four secondlead electrodes 54b, 56, 57b and 59 which extend to respective sidesurfaces 34 through 37. The second internal electrode of the multilayercapacitor 81 is different from the second internal electrode 41 of themultilayer capacitor 31 of the first embodiment in that only one leadelectrode 54b extends to the side surface 34 and only one lead electrode57b extends to side surface 36.

Four second external terminal electrodes 60b, 62, 63b and 65 areelectrically coupled to the four first lead electrodes 54b through 59,respectively. The four second external terminal electrodes are providedon the four side surfaces 34 through 37, respectively. The multilayercapacitor 81 is different from the multilayer capacitor 31 of the firstembodiment in that the second external terminal electrodes 60b and 63bprovided, respectively, in the positions where the first externalterminal electrodes 49 and 51 are provided on the multilayer capacitor31.

By way of example, the multilayer capacitor 81 can be formed by locatingthe third internal electrode 82, the first internal electrode 40b andthe second internal electrode 41b, one above the other with respectivedielectric layers being located therebetween. Irrespective of therelative locations of the internal electrodes, the external terminalelectrodes are arranged such that each of the third external terminalelectrodes 87 through 90 is followed by one of the first externalterminal electrodes 48b through 53 and then followed by one of thesecond external terminal electrodes 60b through 65. This alternatingarrangement is repeated throughout the four side surfaces 34 through 37.The above-described order of stacking the internal electrodes 82, 40band 41b may be changed arbitrarily.

In order to increase the capacity of the multilayer capacitor 81, aplurality of third internal electrodes 82, first internal electrodes 40band second internal electrodes 41b may be provided to form a pluralityof capacitor units. For example, a plurality of third internalelectrodes 82 and a plurality of first internal electrodes 40b may beprovided; a plurality of second internal electrodes 41b and a pluralityof third internal electrodes 82 may be provided; or a plurality of thirdinternal electrodes 82, a plurality of first internal electrodes 40b anda plurality of second internal electrodes 41b may be provided. Theresultant capacitor units are connected in parallel by at least any ofthe third external terminal electrodes 87 through 90, the first externalterminal electrodes 48b through 53 and the second external terminalelectrodes 60b through 65.

Like the first embodiment, external terminal electrodes connected todifferent internal electrodes (that is, external terminal electrodeshaving different polarities) are located on each of the four sidesurfaces 34 through 37. More specifically, first external terminalelectrode 48b, second external terminal electrode 60b and third externalterminal electrodes 87 and 88 are located on the side surface 34; firstexternal terminal electrode 50 and second external terminal electrode 62are located on side surface 35; first external terminal electrode 51b,second external terminal electrode 63b and third external terminalelectrodes 89 and 90 are located on side surface 36; and first externalterminal electrode 53 and second external terminal electrode 65 arelocated on side surface 37.

Therefore, according to the third embodiment of the invention, since theflow of currents on the internal electrodes 40b and 41b can be directedin various directions to effectively cancel magnetic flux and to reducethe lengths of the current paths, the induced inductance components canbe reduced.

Although the arrangement of the third embodiment is different from thatin the first embodiment in that external terminal electrodes havingdifferent polarities are not necessarily adjacent to each other in alllocations, the directions of the current flows on the internalelectrodes 40b and 41b is more diverse than those in the conventionalmultilayer capacitor 1 shown in FIGS. 15 through 17 and the lengths ofthe current paths are shorter. This makes it possible to achieve ahigher reduction of the induced inductance components.

As an alternative to the third embodiment, a multilayer capacitor may beprovided in which only the first and second internal electrodes 40b and41b are provided and the third internal electrode 82 is excluded.Further, the third internal electrode 82 may be formed with leadelectrodes which extend to the side surfaces 35 and 37.

Fourth Embodiment

FIGS. 12 through 14 show a multilayer capacitor 91 according to a fourthembodiment of the present invention. FIG. 12 is a plan view of theexternal appearance of the multilayer capacitor 91. FIG. 13 is a planview of the surface of one of the dielectric layers of the multilayercapacitor 91 having a first internal electrode 40c formed thereon. FIG.14 is a plan view of the surface of one of the dielectric layers of themultilayer capacitor 91 having a second internal electrode 41c formedthereon.

FIGS. 12 through 14 respectively correspond to FIGS. 1 through 3 of thefirst embodiment. In FIGS. 12 through 14, elements corresponding toelements shown in FIGS. 1 through 3 are indicated by like referencenumbers and will not be described here to avoid duplication.

The multilayer capacitor 91 of the fourth embodiment of the inventionresembles the multilayer capacitor 71 of the second embodiment in itsexternal appearance. A first internal electrode 40c has five first leadelectrodes 42, 43, 44c, 45c and 46c which extend to respective sidesurfaces 34, 35 and 36. The multilayer capacitor 91 is different fromthe multilayer capacitor 31 of the first embodiment in that does notinclude a lead electrode corresponding to the lead electrode 47 whichextends to the side surface 37 and in that the positions at which thelead electrodes 44c, 45c and 46c respectively extends to the sidesurfaces 35 and 36 are different from the positions that the leadelectrodes 44 through 46 extend to those surfaces.

Five external terminal electrodes 48, 49, 50c, 51c and 52c areelectrically coupled to the five lead electrodes 42 through 46c,respectively. These external electrodes are provided on the sidesurfaces 34 through 36. The multilayer capacitor 91 is different fromthe multilayer capacitor 31 of the first embodiment in that it does notinclude an external terminal electrode corresponding to the firstexternal terminal electrode 53 and in that the positions of the externalterminal electrodes 50c, 51c and 52c are different from the positions ofthe external terminal electrodes 50 through 52, respectively.

Referring to FIG. 14, a second internal electrode 41c has five leadelectrodes 54, 55, 57c, 58c and 59c, each of which extends to arespective side surfaces 34, 36 and 37. The multilayer capacitor 91 isdifferent from the multilayer capacitor 31 of the first embodiment inthat it does not include a lead electrode corresponding to the leadelectrode 59 which extends to the side surface 35 and in that thepositions of the lead electrodes 57c, 58c and 59c are different from thepositions of the lead electrodes 57 through 59, respectively.

The external terminal electrodes 60, 61, 63c, 64c and 65c which areelectrically coupled to second lead electrodes 54 through 59c,respectively, are provided on the side surfaces 34, 36 and 37. Themultilayer capacitor 91 is different from the multilayer capacitor 31 ofthe first embodiment in that it does not include an external terminalelectrode corresponding to the second external terminal electrode 62 andin that the positions of the external terminal electrodes 63c, 64c and65c are different from the positions of the external terminal electrodes63 through 65, respectively.

In order to increase the capacity of multilayer capacitor 91, aplurality of first internal electrodes 40c and a plurality of secondinternal electrodes 41c can be provided. Pairs of internal electrodes40c, 41c will face one another with a dielectric layer formedtherebetween so as to form respective capacitor units. These capacitorunits will be connected in parallel by at least either the firstexternal terminal electrodes 48 through 52c or the second externalterminal electrodes 60 through 65c.

Like the first embodiment described above, each of the first externalterminal electrodes 48 through 52c of the fourth embodiment of theinvention is arranged so as to alternate with respective ones of thesecond external terminal electrodes 60 through 65c throughout the fourside surfaces 34 through 37. The fourth embodiment is different from thesecond embodiment in this regard.

Therefore, according to the fourth embodiment of the invention, sincethe flow of currents on the internal electrodes 40c and 41c can bedirected in various directions, the various components of inducedmagnetic flux will be cancelled and the lengths of the current pathswill be shortened relative to the prior art of FIGS. 15-17. The fourthembodiment will effectively reduce the induced inductance components toa degree which is similar to that of the first embodiment.

Fifth Embodiment

FIGS. 19 through 21 show a multilayer capacitor 101 according to a fifthembodiment of the present invention. FIG. 19 is a plan view of theexternal appearance of the multilayer capacitor 101. FIG. 20 is a planview of the surface of one of the dielectric layers of the multilayercapacitor 101 having a first internal electrode 40d formed thereon. FIG.21 is a plan view of the surface of one of the dielectric layers of themultilayer capacitor 101 having a second internal electrode 41d formedthereon.

FIGS. 19 through 21 respectively correspond to FIGS. 1 through 3 of thefirst embodiment. In FIGS. 19 through 21, elements corresponding toelements shown in FIGS. 1 through 3 are indicated by like referencenumbers and will not be described here to avoid duplication.

Referring to FIG. 20, a first internal electrode 40d has three firstlead electrodes 44d, 45d and 47d which extend to respective sidesurfaces 35, 36 and 37. The multilayer capacitor 101 is different fromthe multilayer capacitor 31 of the first embodiment in that it does notinclude lead electrodes 42 and 43 which extends to the side surface 34,does not include a lead electrode 46 which extends to the side surface36, and in that the positions at which the lead electrodes 44d, 45d, and47d respectively extends to the side surfaces 35, 36 and 37 aredifferent from the positions that the lead electrodes 44, 45 and 47extend to those surfaces.

The three lead electrodes 44d, 45d and 47d are electrically coupled tothree external terminal electrodes 50d, 51d and 53d respectively. Theseexternal terminal electrodes are provided on the side surfaces 35through 37. The multilayer capacitor 101 is different from themultilayer 31 of the first embodiment in that it does not includeexternal terminal electrodes corresponding to the first externalterminal electrodes 48, 49 and 52 in that the positions of the externalterminal electrodes 50d, 51d and 53d are different from the positions ofthe external terminal electrodes 50, 51 and 53, respectively.

Referring to FIG. 21, a second internal electrode 41d has two leadelectrodes 54d and 57d, each of which extends to respective sidesurfaces 34 and 36. The multilayer capacitor 101 is different from themultilayer capacitor 31 of the first embodiment in that it does notinclude lead electrodes corresponding to the lead electrodes 61, 62, 64and 65 which extends to the side surfaces 34 through 37, respectively,and in that the positions of the lead electrodes 54d and 57d aredifferent from the positions of the lead electrodes 54 and 57,respectively.

Two external terminal electrodes 60d and 63d are electrically coupled tothe two lead electrodes 54d and 57d, respectively, and are provided onthe side surfaces 34 and 36. The multilayer capacitor is different fromthe multilayer capacitor 31 of the first embodiment in that it does notinclude external terminal electrodes corresponding to the secondexternal terminal electrodes 61, 62, 64 and 65, and in that thepositions of the external terminal electrodes 60d and 63d are differentfrom the positions of the external terminal electrodes 60 and 63,respectively.

In order to increase the capacity of multilayer capacitor 101, aplurality of first internal electrodes 40d and a plurality of secondinternal electrodes 41d can be provided. Therefore, according to thefifth embodiment of the invention, since the flow of the currents on theinternal electrodes 40b and 41b can be directed in various directions toeffectively cancel magnetic flux and to reduce the lengths of thecurrent paths, the induced inductance components can be reduced.

Although the arrangement of the fifth embodiment is different from thatin that first embodiment in that external terminal electrodes havingdifferent polarities are not necessarily adjacent to each other in alllocations the directions of the current flows on the internal electrodes40d and 41d is more diverse that those in the conventional multilayercapacitor 1 shown in FIGS. 15 and 17 and the lengths of the currentpaths are shorter. Therefore, this makes it possible to achieve a higherreduction of the induced inductance components.

TEST RESULTS

A sample of each of the multilayer capacitor 31 according to the firstembodiment (embodiment 1), the multilayer capacitor 71 according to thesecond embodiment (embodiment 2), the multilayer capacitor 81 accordingto the third embodiment (embodiment 3), the multilayer capacitor 91according to the fourth embodiment (embodiment 4) and the conventionalmultilayer capacitor 1 (comparative example) was fabricated and ESL ofeach of them was evaluated.

Each sample was formed with outer plan dimensions of 3.2 mm×2.5 mm. Forsamples having six layers of internal electrodes in total, i.e., thosehaving two kinds of internal electrodes such as the multilayercapacitors 31, 71, 91 and 1 (embodiments 1, 2 and 4 and comparativeexample), the stacking of the two kinds of internal electrodes wasrepeated three times (i.e., three pairs of internal electrodes whereused to form three capacitance units). For the sample having three kindsof internal electrodes, i.e., the multilayer capacitor 81 (embodiment3), the stacking of the three kinds of internal electrodes was repeatedtwice.

ESL was obtained using the resonance method. The resonance method is amethod wherein the impedance frequency characteristics of each of thesample multilayer capacitor is measured and ESL is obtained from afrequency f₀ at a minimum point (referred to as series resonance pointbetween the capacity component C_(s) and ESL of the capacitor) using thefollowing equation.

    ESL=1/[(2πf.sub.0).sup.2 ×C.sub.s ]

The measured value of ESL of each sample is shown in the Table 1 below.

                  TABLE 1                                                         ______________________________________                                                      ESL Value (pH)                                                  ______________________________________                                        Embodiment 1    40                                                            Embodiment 2                72                                                Embodiment 3                85                                                Embodiment 4                51                                                Comparative Example                                                                                95                                                       ______________________________________                                    

It is apparent from Table 1 that ESL was suppressed to a greater degreein each of the embodiments 1 through 4 than in the comparative example.The embodiment 1 was most advantageous in reducing ESL. The embodiment 4was more advantageous than the embodiments 2 and 3 in reducing ESL,although it was less advantageous than the embodiment 1.

While the present invention has been described with reference to theillustrated embodiments, for example, it is possible to change positionsand the number of the lead-out electrodes of the internal electrodesvariously and to change the positions and number of the externalterminal electrodes accordingly within the scope of the invention.

As described above, according to the preferred embodiments of thepresent invention, at least either a first or a second internalelectrode is formed with at least three lead electrodes which extendrespectively to at least three of the side surfaces of a capacitor mainbody, and external terminal electrodes which are electrically coupled torespective lead electrodes are provided on respective side surfaces. Asa result, since the flow of currents on the internal electrodes can bedirected in various directions to cancel magnetic flux and to reduce thelengths of the currents path effectively, ESL can be reduced.

With this structure, a high resonance frequency can be achieved and thefrequency band of the capacitor can be increased. Accordingly, amultilayer capacitor according to the invention can accommodateelectronic circuits at higher frequencies than was possible with thecomparative example and can be advantageously used, for example, as abypass capacitor or decoupling capacitor in a high frequency circuit.Further, while a decoupling capacitor used in an MPU (microprocessingunit) must also have the function of a quick power supply (a function ofsupplying power from an amount of electricity charged in the capacitorwhen there is a sudden need for power as in the case of power-up), amultilayer capacitor according to the invention can be used for such anapplication because it has low ESL.

In the embodiments of the present invention described below, thecancellation of magnetic fluxes as described above is further improvedand the lengths of currents are further reduced to achieve moreeffective reduction of ESL.

It should be understood that the foregoing description is onlyillustrative of the invention. Various alternatives and modificationscan be devised by those skilled in the art without departing from theinvention. Accordingly, the present invention is intended to embrace allsuch alternatives, modifications and variances which fall within thescope of the appended claims.

What is claimed is:
 1. A multilayer capacitor, comprising:a capacitormain body having a generally rectangular parallelpiped shape with twoprincipal surfaces in a face-to-face relationship with each other andfour side surfaces connecting said principal surfaces; m capacitor unitsformed in said capacitor main body, m being an integer greater than orequal to one, each of said capacitor units being formed by a respectivepair of first and second internal electrodes disposed in said main bodyin a face-to-face relationship with a dielectric material layerinterposed therebetween to form a capacitor unit; n first externalelectrodes, n being an integer greater than two, each of said firstexternal electrodes being located on a respective one of said sidesurfaces of said capacitor main body, at least one of said firstexternal electrodes being located on each of at least three of said sidesurfaces; said first internal electrode having n first lead electrodes,each of said first lead electrodes extending to and being electricallycoupled to a respective one of said first external electrodes; p secondexternal electrodes, p being an integer greater than one, each of saidsecond external electrodes being located on a respective one of saidside surfaces of said capacitor main body; and said second internalelectrode having p second lead electrodes, each of said second leadelectrodes extending to and being electrically coupled to a respectiveone of said second external electrodes.
 2. The multilayer capacitoraccording to claim 1, wherein said first and second internal electrodesand lead electrodes are arranged in such a manner that when currents ofdifferent polarity are applied to said first and second internalelectrodes, the net induced inductance in the area of all four of saidside surfaces is substantially zero.
 3. The multilayer capacitoraccording to claim 1, wherein p is an integer greater than two and atleast a respective one of said second external electrodes is located oneach of three of said side surfaces.
 4. The multilayer capacitoraccording to claim 3, wherein on any given side surface, no two externalelectrodes which are electrically coupled to the same one of said firstand second internal electrodes are located adjacent one another.
 5. Themultilayer capacitor according to claim 3, wherein n is four and whereina respective one of said first external electrodes is located on each ofsaid four side surfaces.
 6. The multilayer capacitor according claim 5,wherein p is four and wherein a respective one of said second externalelectrodes is located on each of said four side surfaces.
 7. Themultilayer capacitor according to claim 6, wherein said first and secondexternal electrodes are arranged alternately along said side surfacessuch that no two external electrodes electrically coupled to the sameinternal electrode are located adjacent one another.
 8. The multilayercapacitor according to any one of claims 1 through 7, wherein m is aninteger greater than 1 and wherein each of said capacitor units areconnected in parallel via at least either said first or second externalterminal electrodes.
 9. The multilayer capacitor according to claim 1,wherein at least two of said first external electrodes are located on asame one of said side surfaces.
 10. The multilayer capacitor accordingto claim 9, wherein at least two of said second external electrodes arelocated on a same one of said side surfaces.
 11. The multilayercapacitor according to claim 1, wherein each of said capacitor unitsfurther includes a third internal electrode disposed in said main bodyin a face-to-face relationship with at least either said first or secondinternal electrodes with a dielectric material layer interposedtherebetween.
 12. The multilayer capacitor of claim 11, furtherincluding at least two third external electrodes located on said sidesurfaces and wherein said third internal electrode has at least twothird lead electrodes which extend to and are electrically coupled torespective ones of said at least two third external electrodes.
 13. Themultilayer capacitor according to claim 12, wherein all of said first,second and third internal electrodes are interposed with respect to oneanother such that no two external electrodes which are coupled to thesame internal electrode are located adjacent one another.
 14. Themultilayer capacitor according to any one of claims 1 through 6, whereinall of said external terminal electrodes are arranged such that they arenot located adjacent to another external terminal electrode connected tothe same internal electrode.
 15. The multilayer capacitor according toany one of claims 1, 2, 3, 4, 5 and 7, wherein at least one of saidexternal terminal electrodes is provided on each of said four sidesurfaces.
 16. The multilayer capacitor according to any one of claims 1through 7, wherein said first and second internal electrodes aregenerally planar and lie in planes which are generally parallel to oneanother.
 17. The multilayer capacitor according to claim 16, whereinsaid planes are generally parallel to the principal surfaces of saidcapacitor main body.
 18. The multilayer capacitor according to claim 16,wherein said first and second internal electrodes are generallyrectangular in shape as viewed along said planes.
 19. The multilayercapacitor according to claim 1, wherein n is three and wherein arespective one of said first external electrodes is located on each ofthree of said side surfaces.
 20. The multilayer capacitor according toclaim 19, wherein p is two and wherein a respective one of said secondexternal electrodes is located on each of two of said side surfaces. 21.The multilayer capacitor according to claim 20, wherein said first andsecond external electrodes are arranged alternately along said sidesurfaces such that no two external electrodes electrically coupled tothe same internal electrode are located adjacent to another along thesame side surface.
 22. The multilayer capacitor according to claim 20,wherein said second external electrodes are arranged on opposite ones ofsaid side surfaces.
 23. The multilayer capacitor according to claim 22,wherein said side surfaces are first, second, third and fourth sidesurfaces, a respective one of said first external electrodes is locatedon each of said first, second and third side surfaces, one of saidsecond external electrodes is located on said fourth side surface andanother of said second external electrodes is located on said secondside surface.
 24. The multilayer capacitor according to claim 23,wherein said second and fourth side surfaces are located opposite oneanother.
 25. The multilayer capacitor according to claim 19, wherein mis an integer greater than 1 and wherein each of said capacitor unitsare connected in parallel via at least either said first or secondexternal terminal electrodes.
 26. The multilayer capacitor according toany of claims 19 through 24, wherein said first and second internalelectrodes are generally planar and lie in planes which are generallyparallel to one another.